U.S. patent number 3,957,827 [Application Number 05/515,771] was granted by the patent office on 1976-05-18 for hydrogenation of carboxylic acid anhydrides to lactones or esters by homogeneous catalysis.
This patent grant is currently assigned to Sun Ventures, Inc.. Invention is credited to James E. Lyons.
United States Patent |
3,957,827 |
Lyons |
May 18, 1976 |
Hydrogenation of carboxylic acid anhydrides to lactones or esters
by homogeneous catalysis
Abstract
.gamma.-Lactones may be selectively prepared by the
hydrogenation of cyclic carboxylic acid anhydrides under mild
conditions in a homogeneous solution in the presence of a ruthenium
catalyst of the formula ##EQU1## WHEREIN X is hydrogen, chlorine,
bromine, iodine, or lower alkyl; n is an integer of from 0-2, but
when n is 2, X may be the same or different; L is a neutral ligand,
olefin, or CO; y is an integer of from 0-3, but when y is 2 or 3, L
may be the same or different; R.sub.6, R.sub.7 and R.sub.8 are
lower alkyl, cycloalkyl of from 5 to 15 carbon atoms, aryl, benzyl,
or a bidentate ligand, and each of the R groups may be the same or
different; and x is an integer of from 1-3. In a like manner,
esters may be prepared in high yields by the selective
hydrogenation of acyclic carboxylic acid anhydrides.
Inventors: |
Lyons; James E. (Wallingford,
PA) |
Assignee: |
Sun Ventures, Inc. (St. Davids,
PA)
|
Family
ID: |
24052670 |
Appl.
No.: |
05/515,771 |
Filed: |
October 17, 1974 |
Current U.S.
Class: |
549/307; 502/161;
549/299; 549/311; 560/1; 560/122; 502/155; 502/162; 549/302;
549/325; 560/106; 560/265 |
Current CPC
Class: |
C07D
315/00 (20130101); C07C 67/00 (20130101); C07C
67/00 (20130101); C07C 69/14 (20130101); C07C
67/00 (20130101); C07C 69/56 (20130101) |
Current International
Class: |
C07D
315/00 (20060101); C07C 068/00 (); C07D 307/20 ();
C07D 307/88 () |
Field of
Search: |
;260/343.3,343.6,488R,469,476R,468R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Patten; James A.
Attorney, Agent or Firm: Hess; J. Edward Johnson; Donald R.
Back; Stanford M.
Claims
The invention claimed is:
1. A process for the selective hydrogenation of acyclic and cyclic
carboxylic acid anhydrides to form esters or lactones comprises
reacting hydrogen with (1) an acyclic compound of the formula:
##EQU11## wherein R and R.sub.1 are lower alkyl, cycloalkyl of from
5 to 15 carbon atoms, or aryl, wherein the R groups may be the same
or different; or (2) a cyclic compound of the formula: ##EQU12##
wherein R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are hydrogen, lower
alkyl, cycloalkyl of from 5 to 15 carbon atoms, or aryl, wherein
each of the R groups may be the same or different; and wherein the
R groups, taken together, may form a saturated or aromatic ring;
said reaction being carried out in a homogeneous solution in the
presence of a ruthenium catalyst of the formula: ##EQU13## wherein
X is hydrogen, chlorine, bromine, iodine, or lower alkyl; n is an
integer of from 0-2, but when n is 2, X may be the same or
different; L is a neutral ligand, olefin, or CO; y is an integer of
from 0-3, but when y is 2 or 3, L may be the same of different;
R.sub.6, R.sub.7 and R.sub.8 are lower alkyl, cycloalkyl of from 5
to 15 carbon atoms, aryl, benzyl, or a bidentate ligand, and each
of the R groups may be the same or different; and x is an integer
of from 1-3, at a temperature of from about 50.degree. to
150.degree.C., and at a hydrogen pressure of from about 40 to 400
psi.
2. The process according to claim 1 wherein the anhydride is acetic
anhydride and the ester is ethyl acetate.
3. The process according to claim 1 wherein the anhydride is
succinic anhydride and the lactone is .gamma. -butyrolactone.
4. The process according to claim 1 wherein the anhydride is
phthalic anhydride and the lactone is phthalide.
5. The process according to claim 1 wherein the catalyst is
[RuCl.sub.2 (Ph.sub.3 P).sub.3 ].
6. The process according to claim 1 wherein the catalyst is
RuHCl(PPh.sub.3).sub.3.
7. The process according to claim 1 wherein the catalyst is
RuCl.sub.2)PPh.sub.2 CH.sub.3).sub.3.
8. The process according to claim 1 wherein part of the anhydride
starting material is hydrolyzed to the corresponding acid, the acid
recovered and dehydrated, and the resulting anhydride recycled to
the reaction.
9. The process according to claim 1 wherein the reaction is carried
out in the presence of a dehydrating agent.
10. The process according to claim 9 wherein the dehydrating agent
is a molecular sieve or MgSO.sub.4.
11. The process according to claim 1 wherein the catalyst is
present in amounts of 10.sup..sup.-1 to 10.sup..sup.-4 moles per
mole of anhydride starting material present.
Description
BACKGROUND OF THE INVENTION
This invention relates to an improved process for the selective
hydrogenation of acyclic and cyclic carboxylic acid anhydrides to
esters and lactones. More particularly, this invention relates to
the selective conversion of said anhydrides to esters and lactones
respectively hydrogenating hydrogenating them under mild conditions
in the presence of an organometallic ruthenium complex catalyst in
homogeneous solution.
It is known, for example, from Kanetaka et al., Japan 71, 33,030,
that succinic anhydride can be hydrogenated to .gamma.
-butyrolactone using heterogeneous catalysts which necessitate
vigorous conditions: 2000.degree.-300.degree.C., 1500-3000 psi
H.sub.2. Reaction is unselective and tetrahydrofuran is usually
formed as a by-product.
SUMMARY OF THE INVENTION
In accordance with the present invention, it has now been found
that acyclic and cyclic carboxylic acid anhydrides can be
hydrogenated to form the corresponding esters and lactones
respectively by by carrying out the reaction in the presence of a
homogeneous ruthenium catalyst of the formula ##EQU2## WHEREIN X is
hydrogen, chlorine, bromine, iodine, or lower alkyl; n is an
integer of from 0-2, but when n is 2, X may be the same or
different; L is a neutral ligand, olefin, or CO; y is an integer of
from 0-3, but when y is 2 or 3, L may be the same or different;
R.sub.6, R.sub.7 and R.sub.8 are lower alkyl, cycloalkyl of from 5
to 15 carbon atoms, aryl, benzyl, or a bidentate ligand, and each
of the R groups may be the same or different; and x is an integer
of from 1-3, at temperatures in the range of from about 50.degree.
150.degree.C., preferably 90.degree. to 110.degree.C., and at about
40 to 400 psi H.sub.2, preferably 100 to 150 psi. The reaction is
characterized by being selective, often quantitative in yield, and
most desirably does not proceed beyond the lactone or ester.
These reactions may best be described by the following reaction
schemes: ##EQU3## wherein R and R.sub.1 are lower alkyl, cycloalkyl
of from 5 to 15 carbon atoms, or aryl; wherein the R groups may be
the same or different; and ##EQU4## wherein each of R.sub.2,
R.sub.3, R.sub.4 and R.sub.5 is hydrogen, lower alkyl, cycloalkyl
of from 5 to 15 carbon atoms, or aryl; wherein each of the R groups
may be the same of different; and wherein the R groups, when taken
together may form a saturated, or unsaturated, ring having from 5
to 8 carbon atoms, or an aromatic or condensed aromatic ring.
DESCRIPTION OF THE INVENTION
The starting materials comprise acyclic and cyclic carboxylic acid
anhydrides, as above-defined. More particularly, the acyclic
anhydrides are comprised of compounds of the formula ##EQU5##
wherein R and R.sub.1 are as defined above in Equation 1. Examples
of acyclic anhydrides coming within the purview of this invention
include acetic anhydride, propionic anhydride, benzoic acid
dianhydride and mixed anhydrides of similar structure. When these
compounds are hydrogenated in accordance with the process of this
invention, there are obtained the corresponding esters of the
formula ##EQU6## wherein R and R.sub.1 are as defined above. The
ester products include such compounds as ethyl acetate, butyl
propionate, benzyl benzoate, and the like.
The cyclic anhydrides are comprised of compounds of the formula
##EQU7## wherein each of R.sub.2, R.sub.3, R.sub.4 and R.sub.5 is
as defined above in Equation 2. Examples of cyclic anhydrides
falling within the scope of the invention include succinic
anhydride, glutaric anhydride and the like. When these compounds
are reacted in accordance with the disclosed process, there are
obtained the corresponding lactones of the formula ##EQU8## wherein
each of R.sub.2, R.sub.3, R.sub.4 and R.sub.5 is as defined above,
as for example .gamma. -butyrolactone. In addition to the
foregoing, the R.sub.2.sub.-5 groups taken together may form
bicyclic compounds, including those of the formula ##SPC1##
as for example phthalide from phthalic anhydride, the corresponding
.gamma. -lactone from naphthalene-1,2-dicarboxylic acid anhydride
and the like.
Each of the aforedescribed products is known in the art and has
established utilities. Ethyl acetate, for example, is a fast-drying
solvent with applications in cellulose, shellac, vinyl resins, and
the like. Likewise, .gamma. -butyrolactone is an important
industrial solvent for cellulose acetate or polystyrene as well as
an intermediate for N-methyl-pyrolidone, vinyl-pyrolidone,
piperidine and the like. Phthalide is useful as a co-monomer in
polymer formulations, i.e. formaldehyde polymers, and in the
synthethis of dyestuffs. Thus it may be said that esters and
lactones generally have well-established wide industrial
applications, and that the esters in particular have wide utility
as solvents and plasticizers.
The ruthenium catalyst of this process, as mentioned above, has the
formula ##EQU9## wherein X is hydrogen, chlorine, bromine, iodine,
or lower alkyl; n is an integer of from 0-2, but when n is 2, X may
be the same or different; L is a neutral ligand, olefin, or CO; y
is an integer of from 0-3, but when y is 2 or 3, L may be the same
or different; R.sub.6, R.sub.7 and R.sub.8 are lower alkyl,
cycloalkyl of from 5 to 15 carbon atoms, aryl, benzyl, or a
bidentate ligand, and each of the R groups may be the same or
different; and x is an integer of from 1-3. Included amongst these
compounds are the catalysts RuCl.sub.2 (PPh.sub.3).sub.3,
RuHCl(PPh.sub.3).sub.3, RuCl.sub.2 (CO)(PPh.sub.3).sub.2 (C.sub.8
H.sub.12), RuBr.sub.2 (PPh.sub.3).sub.3, RuHBr(PPh.sub.3).sub.3,
RuCl.sub.2 (PPh.sub.2 CH.sub.3).sub.3, of which RuCl.sub.2
(PPh.sub.3).sub.3 is preferred. See Hallman et al., J. Chem. Soc.
(A), 3143, (1968), for the preparation of these compounds. Also
useful are bidentate ligand catalysts such as Ru(C.sub.10 H.sub.8)
(diphos).sub.2, and Ru(diphos).sub.2. See Chatt et al., J. Chem.
Soc., 843, (1965), for their preparation.
The process may readily be carried out by contacting the acid
anhydride with the ruthenium catalyst in the presence of a solvent
at temperatures in the range of from about 50.degree. to
150.degree.C., and preferably 90.degree. to 110.degree.C., for a
period of from 1 to 20 hours, depending upon the reactants, at a
pressure of from about 40 to 400 psi H.sub.2, and preferably 100 to
150 psi. The solvent is desirably an aromatic hydrocarbon such as
toluene or xylene but other unreactive solvents such as
chlorocarbons, fluorocarbons, ethers and the like are also
suitable. The ratio of starting material to solvent is most
desirably in the range of from 0.1 to 1.0, and preferably 0.3 to
0.7. The amount of catalyst employed should be about 10.sup..sup.-1
mole to 10.sup..sup.-4 mole per mole of starting material, and
preferably 10.sup..sup.-2 mole to 10.sup..sup.-3 mole. The ester or
lactone product is conveniently recovered by distillation,
crystallization or other conventional methods.
It will be noted in both Equations 1 and 2 above that water is
formed as a by-product of this hydrogenation reaction with the
result that for every mole of product formed, 1 mole of water is
formed which then hydrolyzes 1 mole of starting material to its
corresponding acid in accordance with the following overall
reaction scheme, using a cyclic anhydride as an example:
##EQU10##
Thus it will be understood from the above that while the yield of
desired lactone product is 50% by weight, it represents 100%
theoretical yield. Moreover, the hydrolyzed acid may readily be
recovered dehydrated, and recycled to the reactor with little, if
any, resultant loss by weight of starting compound.
It will also be evident from the foregoing that if an effective
water scavanger, i.e., dehydrating agent, such as a molecular
sieve, MgSO.sub.4, or the like is added to the reaction medium,
most if not all of the attendant hydrolysis and resulting
dehydration and recycle of starting anhydride may be avoided, with,
of course, increased yields per pass.
The invention will now be illustrated by the following
examples.
EXAMPLE 1
Succinic anhydride, 2.0 grams, toluene, 4.0 ml and [RuCl.sub.2
(Ph.sub.3 P).sub.3 ], 0.1 gram are stirred at 100.degree.C under
150 psi H.sub.2 for 10 hours. During the reaction the anhydride
dissolves over the first 2 hours to form an orange solution which
absorbs hydrogen steadily. After hydrogen adsorption has stopped,
after 8 hours, the mixture is allowed to stir for an additional 2
hours under 150 psi H.sub.2 and 100.degree.C. The mixture is cooled
to precipitate the acid formed during reaction and the solution
contains only .gamma.-butyrolactone and less than 1% of
unidentified impurities.
EXAMPLE 2
The procedures of Example 1 are repeated, but acetic anhydride and
phthalic anhydride, respectively, are substituted for the succinic
anhydride starting material of this previous example. The results
obtained are summarized in Table I below. The results of Example 1
are included.
TABLE I
__________________________________________________________________________
STARTING CONVERSION SELEC- CATALYST MATERIAL PRODUCT (THEORETICAL)
TIVITY
__________________________________________________________________________
[RuCl.sub.2 (Ph.sub.3 *P).sub.3 ] Acetic Ethyl Acetate 100% 95%
Anhydride [RuCl.sub.2 (Ph.sub.3 P).sub.3 ] Phthalic Phthalide 100%
100% Anhydride [RuCl.sub.2 (Ph.sub.3 P).sub.3 ] Succinic
.gamma.-Butyrolactone 100% 99% Anhydride
__________________________________________________________________________
*Ph=phenyl
EXAMPLE 3
In accordance with the process of Example 2, but substituting
RuHCl(PPh.sub.3).sub.3 as the catalyst, there are obtained each of
the respective products in good yield.
EXAMPLE 4
In accordance with the process of Example 1, but substituting
RuBr.sub.2 (PPh.sub.3).sub.3 as the catalyst, there is obtained
.gamma. -butyrloactone in good yield.
EXAMPLE 5
In accordance with the process of Example 1, but substituting
RuCl.sub.2 (PPh.sub.2 CH.sub.3).sub.3 as the catalyst, there is
obtained .gamma. butyrolactone in good yield.
EXAMPLE 6
Example 1 is repeated except that the catalyst is Ru(diphos).sub.2,
the hydrogen pressure is 400 psi, and the temperature is
125.degree.C. .gamma. -butyrolactone is provided in good yield.
* * * * *